Reservoir snag prolongs risk of sewage backups

Main reservoir won't be operational until end of next decade, filings say

March 19, 2011

The Deep Tunnel system was intended not only to curb water pollution, but also to prevent sewage from backing up into basements, a soggy routine for many Chicago-area residents after big storms.

Officials in charge of the massive project promised that flood-control reservoirs near O'Hare International Airport, southwest suburban McCook and south suburban Thornton would capture deluges of storm runoff funneled into giant tunnels and dramatically reduce flooding. When officials unveiled the project in 1972, they projected it would be complete by 1983.

But in recent regulatory filings, the Metropolitan Water Reclamation District revealed that its main reservoir, designed to be 11 times larger than Soldier Field, won't be operational until the end of the next decade. They blame the latest delay on declining federal support and the recession, which dried up demand for limestone at a McCook quarry that will be converted into the district's biggest retention pond.

As a result, Chicago and three dozen suburbs, stretching from Wilmette to Western Springs, are expected to remain at risk for sewage backups for years to come. Areas most prone to basement flooding include some of the city's poorest neighborhoods, according to a study commissioned by the Chicago Department of Water Management.

"The district said they would capture and treat all of this runoff," said Rob Sulski, an Illinois EPA engineer who oversees the Chicago River. "But they just can't handle what Mother Nature is delivering."